1. Field of the Invention
The present invention relates to an inspection system for and a method of confirming, bidirectionally at all times on a real-time basis, the quality and soundness of a transporting means, a transporting container, or a transported object while the object is being transported by or handled on a vehicle, a ship, an airplane, or the like.
Specifically, the present invention is concerned with a system for fetching measured waveform data as to the confirmation of the soundness of a transported object, a transporting means, a transportation container, and a transporting and handling status after the object is unloaded from an object processing plant and until it is delivered to its destination, into a server via a dedicated wired or wireless communication network, continuously monitoring the soundness of the transported object, the transporting means, the transportation container, and the transporting and handling status at a remote transported object monitoring office on a real-time basis based on the measured waveform data supplied from the server via the Internet Web, and allowing bidirectional data to be exchanged between the remote transported object monitoring office and an object transporting or handling spot for the purpose of confirming the soundness.
The transported object may, for example, be any of nuclear fuel assemblies of UO2, MOX fuels and used fuel assemblies, nuclear fuel substances (UO2 powder, UF6 gas, etc.), and high- and low-level radioactive wastes.
2. Description of the Related Art
Among conventional apparatus for and methods of inspecting the soundness of transported objects while they are being transported and handled are measuring apparatus for storing the values of accelerations/frequencies applied to the objects being transported and times at which the accelerations/frequencies are applied, as typically disclosed in Japanese laid-open patent publications Nos. 55-131774 and 7-280091 and Japanese laid-open utility model publication No. 6-37720. According to the disclosed systems, after the transported object has arrived at a destination, the stored data are retrieved from the measuring apparatus and processed and analyzed by a personal computer (PC), and the analyzed results are confirmed on a PC display screen and in an output format. As a result, the soundness of the transporting means, the transportation container, and the transported object can be determined while the object is being transported and handled, and after the transported object has arrived at the destination, the transportation status information from the transporting agency, which represents a road status and locations where large impact vibrations were applied to the transporting car, is checked against the analyzed results, for thereby finally judging the soundness of the transported object and subsequently improving transporting conditions.
The above inspection system for and method of confirming the soundness of the transported object fail to handle accidents and trouble during the transportation of the object because the soundness of the transported object is judged after the transportation of the object is completed.
For example, even if a radioactive substance in excess of a reference value (trigger level) happens to be emitted from a nuclear fuel substance due to an accident while the nuclear fuel substance is being transported, it is only after the nuclear fuel substance arrives at its destination that an increased radiation exposure or damage to the transportation container or the fuel assembly is noticed.
If a transportation container storing a dangerous substance is damaged due to some trouble while the dangerous substance is being transported, then the dangerous substance stored in the transportation container tends to gradually leak out as a gas, a fluid, or a solid during the transportation, and the damage to the transportation container is liable to become large due to vibrations and with time. The dangerous substance may be emitted in an increasing quantity which may lead to a serious accident.
For preventing the quality of the object from being lowered while it is being transported, the temperature and humidity in the transportation container must be maintained at a constant level at all times. If some trouble occurs during the transportation of the object, greatly changing the temperature and humidity in the transportation container, and the object is transported to its destination at the changed temperature and humidity, then it is noticed only at the destination after the object has been transported that the object has been transported to the destination with the temperature and humidity failing to satisfy predetermined levels, and that the soundness and quality of the transported object has been impaired.
According to a conventional apparatus and method for confirming and inspecting the soundness of a nuclear fuel assembly for use in a light water reactor at the time the nuclear fuel assembly is transported and handled, the soundness of a nuclear fuel assembly is confirmed and inspected as follows:
As well known in the art, after a nuclear fuel assembly for use in a light water reactor is manufactured by a nuclear fuel processing facility and inspected upon shipment, it is stored in a transportation container and transported to a nuclear power plant by a transporting means such as a vehicle, which may be a truck, a trailer, or a cargo train, or a ship.
After the nuclear fuel assembly stored in the transportation container is transported, the nuclear fuel assembly is confirmed and inspected in order to confirm the soundness of the nuclear fuel assembly at the time it is transported and handled, as follows:
A mechanical ON/OFF accelerometer which is mounted on the transportation container for confirming a temporary impact acceleration is confirmed for its tripped state (when a temporary impact acceleration in excess of a predetermined value is applied to the mechanical ON/OFF accelerometer, the ON/OFF accelerometer is operated into a tripped state).
The nuclear fuel assembly is removed from the transportation container, and inspected for its appearance within a reactor building.
The above two confirming and inspecting processes are carried out to confirm that there is no problem with respect to the soundness of the nuclear fuel assembly as it is transported and handled, after which the nuclear fuel assembly is guaranteed.
If the ON/OFF accelerometer mounted on the transportation container is found tripped in the confirming process after the nuclear fuel assembly is transported, then the transportation container including the nuclear fuel assembly which has been transported is transported back to the nuclear fuel processing facility.
FIG. 1 of the accompanying drawings schematically shows a structure of a general ON/OFF accelerometer. The ON/OFF accelerometer shown in FIG. 1 operates as follows: When an acceleration in excess of a certain level is applied to mass 1, spring 2 supporting mass 1 is flexed, causing pin 3 mounted on the tip end of mass 1 to move downwardly in FIG. 1. As a result, upper spring 4 is released from its engaged state to allow seat 5 to move to the left in FIG. 1, whereupon the ON/OFF accelerometer is tripped.
The ON/OFF accelerometer is usually mounted on each transportation container and its vibroisolating system for appropriately detecting applied accelerations applied while the transportation container is being transported and handled.
FIGS. 2 and 3 of the accompanying drawings show a structure of a nuclear fuel assembly for use in a boiling water reactor nuclear power plant, as a typical nuclear fuel assembly to be transported.
As shown in FIG. 2, the nuclear fuel assembly has a plurality of nuclear fuel rods 6 arranged in an 8×8, 9×9, or 10×10 grid pattern, and water rod 7 disposed centrally in the array of nuclear fuel rods 6. Nuclear fuel rods 6 have upper and lower ends thereof supported respectively by upper and lower tie plates 8, 9, and bundled in the grid pattern by a plurality of spacers 10 that are spaced axially along nuclear fuel rods 6.
Each of nuclear fuel rods 6 comprises cover tube 6a filled with a nuclear fuel substance such as UO2 pellets 11 or MOX pellets (mixed oxide pellets) 12. As shown in FIG. 3, nuclear fuel rod 6 and spacer ring 13 of each spacer 10 are held in contact with each other.
Structural details of the object to be transported have been described above. Details of a conventional process of transporting the object will be described below.
For transporting nuclear fuel assemblies or substances, a predetermined transportation route from the starting point to the destination, major spots to pass through on the transportation route, and planned passing and arrival times at those major spots are applied for in advance with a competent authority.
During the actual transportation, a telephonic exchange of information is made at all times between accompanying security vehicles, the driver of the transporting vehicle, and a remote control center about each passing spot applied for and how many minutes the transporting vehicle leads or lags behind a planned time at which the transporting vehicle is supposed to pass through the passing spot, and the latest exchanged information is sent via telephone from the remote control center to the competent authority a certain period of time before a planned time when the transporting vehicle is actually supposed to pass through the passing spot.
When the transporting vehicle passes through a passing spot, the error or difference between the actual time when the transporting vehicle passes through the passing spot and the planned time when the transporting vehicle is supposed to pass through the passing spot is sent from the remote control center to the competent authority.
According to the above communication system, all information between the remote control center and the travelling accompanying security vehicles is exchanged via telephone, and displayed on a map in the remote control center for grasping traveling status information of the transporting vehicle.
One problem with the above communication system is that since the traveling position of the transporting vehicle and its time information are manually transmitted via telephone, the positional and time information may possibly be transmitted in error. Furthermore, because the information is sent based on a bidirectional telephonic exchange, the bidirectional communications are temporarily interrupted when the transporting vehicle runs through a tunnel. Accordingly, the positional and time information may not accurately be transmitted in real-time.
If the transporting vehicle and the accompanying security vehicles travel in error along a route different from the applied-for route, then since the remote control center is unable to confirm the status of the transporting vehicle in real-time, no information may be sent from accompanying security vehicles or the driver of the transporting vehicle to the remote control center until the transporting vehicle comes near a next planned spot which has been applied for. During this time, the transporting vehicle travels along the wrong route, resulting in a possibly serious situation.
If the transporting vehicle suffers an accident, or particularly if the transporting vehicle suffers a serious impact accident which tends to allow the transported nuclear fuel assembly or substance to be emitted out of the transportation container, then it is necessary for the accompanying security vehicles and the remote control center to confirm bidirectionally in real-time the locations of police departments, schools, hospitals, and city, town, and village offices within a sphere several to several tens km across around the accident spot on a PC display screen in view of the special incident of nuclear fuel substance emission.
When such a need arises, it has been customary to wait for the telephonic transmission of information from the accompanying security vehicles or following cars near the trouble location. From the time the information is received on, the competent authority estimates the trouble spot on a map and checks information about major institutions within several km from the trouble spot. This process is considerably time-consuming, and causes a delay in sending necessary information and a failure to collect accurate information.
For confirming and inspecting the transportation status and the quality soundness of the transported object while the object is being transported and handled, it has been the conventional practice to confirm a signal, i.e., ON/OFF information, from the mechanical ON/OFF accelerometer in the measuring apparatus, directly judge data including temperature, humidity, acceleration, and gas concentration data from the measuring apparatus, or collect, process, and analyze stored data from the measuring apparatus through a PC and judge the analyzed data on the PC display screen or in an output format.
The conventional process has suffered a first problem with respect to sampled contents of the measured data used for confirming the soundness of the transported object and a method of judging the sampled contents. One example of the first problem will be described below with regard to an apparatus for and a method of confirming and inspecting the soundness of a nuclear fuel assembly while it is being transported and handled, for use in a light water reactor.
Events that impair the soundness of the nuclear fuel assembly shown in FIG. 2 while it is being transported and handled, will be described below.
(1) Cracking and breaking of UO2 pellets 11 and MOX pellets 12.
(2) Damage to nuclear fuel components such as spacers 10.
The above phenomena (1), (2) may possibly be caused when an intermittent impact acceleration or a continuous impact acceleration in excess of a certain level is applied to the nuclear fuel assembly shown in FIG. 2 while it is being transported and handled.
(3) Fretting of the surface of cover tubes 6a of nuclear fuel rods 6. Fretting occurs on the surface of cover tubes 6a when spacer springs 13 and nuclear fuel rods 6 rub against each other due to vibrations while the nuclear fuel assembly shown in FIG. 2 is being transported. If an impact acceleration in excess of a certain level is intermittently or continuously applied to the nuclear fuel assembly shown in FIG. 2 while it is being transported, then the surface of cover tubes 6a suffers more fretting.
The nuclear fuel assembly can be directly checked for the above defects (1) through (3) by disassembling the nuclear fuel assembly and conducting a detailed inspection on the components thereof after the nuclear fuel assembly is transported. Actually, however, the nuclear fuel assembly cannot be disassembled because the transported nuclear fuel assembly is placed in a transportation container replacement facility or a nuclear power plant as a final destination.
Therefore, it is practically difficult to directly inspect the soundness of the nuclear fuel assembly after it is transported. According to the conventional inspection process, the ON/OFF accelerometer shown in FIG. 1 is mounted on the transportation container and its vibroisolating system, and the soundness of the nuclear fuel assembly is judged based on a tripped state of the ON/OFF accelerometer due to a temporary impact acceleration in excess of a certain level applied to the nuclear fuel assembly while it is being transported and handled.
The above conventional inspection process is unable to sample acceleration data continuously. In addition, because the ON/OFF accelerometer is tripped by a single (temporary) impact acceleration in excess of a preset value, the conventional inspection process suffers the following drawbacks:
(1) There is no way of confirming the cause of an impact acceleration applied to trip the ON/OFF accelerometer. That is, it is impossible to tell whether the ON/OFF accelerometer is tripped while the transportation container storing the nuclear fuel assembly therein is being handled or transported. It is also impossible to tell whether the ON/OFF accelerometer is tripped by a temporary acceleration or an intermittent or continuous acceleration while the transportation container is being transported.
(2) Since an intermittent or continuous acceleration cannot be sampled, failures of a vibration system of the transportation container and a fastened state of the transportation container cannot be confirmed. Specifically, failures such as deterioration, damage, etc. of a vibroisolating system such as vibroisolating rubber members for the transportation container cannot be confirmed for each transporting session. Failures such as damage to suspension systems of vehicles such as trucks as the transporting means cannot be confirmed for each transporting session. Furthermore, failures of a fastened state between the transportation container and the transporting means cannot be confirmed for each transporting session.
Consequently, events that are detrimental to the soundness of the nuclear fuel assembly while it is being transported cannot accurately be determined for each transporting session.
(a) Since events that are detrimental to the soundness of the nuclear fuel assembly cannot accurately be determined, even when the ON/OFF accelerometer is tripped merely by a single temporary impact acceleration, the nuclear fuel assembly which has in fact no problem is judged as a defective product and needs to be returned to the nuclear fuel processing facility for detailed inspection. This procedure is highly uneconomical.
(b) Due to a failure of the vibroisolating system of the transportation container, an intermittent or continuous acceleration lower than the level for tripping the ON/OFF accelerometer may be applied to the nuclear fuel assembly, tending to adversely affect the soundness of the nuclear fuel assembly, e.g., to increase fretting on the nuclear fuel assembly. However, unless the ON/OFF accelerometer is tripped, the nuclear fuel assembly is accepted as a defect-free product.
In view of the above drawbacks associated with the use of the ON/OFF accelerometer, it has been proposed to use another inspecting means instead of the ON/OFF accelerometer for collecting data representing continuously generated acceleration.
FIG. 4 of the accompanying drawings shows a conventional inspecting means for use in an advance confirmation transporting test using a dummy fuel assembly.
As shown in FIG. 4, the conventional inspecting means has small-size acceleration sensor 14 fixed by an adhesive or the like to a transportation container and its vibroisolating system or a location where vibration data are necessary. Distortion amplifier 16 and large-size data recorder 17 are connected to acceleration sensor 14 by cable 15. Distortion amplifier 16 is energized by power supply 18. An acceleration detected by acceleration sensor 14 is amplified by distortion amplifier 16, and data of the amplified acceleration is collected by data recorder 17.
The collected data, i.e., a reproduced signal, is in the form of an analog signal. To process the collected data as a digital signal, large-size recorder processor 19 is connected to data recorder 17. Pen recorder 20 is also connected to data recorder 17 for outputting waveform data of the collected data.
The conventional inspecting means shown in FIG. 4 is not applied to real sessions for transporting nuclear fuel assemblies. Heretofore, the conventional inspecting means shown in FIG. 4, which is of a relatively large scale, is used to obtain acceleration data in an advance confirmation transporting test using a dummy fuel assembly. In actual processes for transporting real nuclear fuel assemblies, however, the acceleration sensor is not applied to the nuclear fuel assembly as it is highly difficult to install the large-scale inspecting means in each transporting session. In actual transporting processes, therefore, it has not been practiced to obtain continuous accelerations and frequency data thereof.
If the above inspecting means is applied to usual nuclear fuel assembly processes, then the following problems arise:
(a′) Since the overall system is large in size, it is difficult to place data recorder 17 on the transporting means (a truck, a trailer, or the like).
(b′) Data recorder 17 requires large-capacity power supply 18, and needs to be de-energized at every given period of time to replace the recording tape as the data recording time thereof is short.
(c′) For analyzing and evaluating acceleration data after the transporting session, it is necessary to remove the recording tape from data recorder 17, place the recording tape into large-size recorder processor 19, and perform a process of analyzing the data recorded on the recording tape. Consequently, it is difficult to process the data quickly on site after the transporting session.
(d′) Since acceleration sensor 14 and data recorder 17 are connected to each other by cable 15, cable 15 needs to be extended to the location where data recorder 17 is installed. Cable 15 thus extended often has a length of several tens m or more, and cannot be handled with ease. The long cable tends to pick up noise to be added to the detected signal, and hence the detected data becomes necessarily low in accuracy.
(e′) Acceleration sensor 14 cannot be attached directly to nuclear fuel rods 6 and fuel components.
The conventional process has suffered a second problem with respect to known measuring apparatus for storing the values of accelerations/frequencies applied to the objects being transported and times at which the accelerations/frequencies are applied, as typically disclosed in Japanese laid-open patent publications Nos. 55-131774 and 7-280091 and Japanese laid-open utility model publication No. 6-37720. According to the known measuring apparatus, after the transported object has arrived at a destination, the stored data are retrieved from the measuring apparatus and processed and analyzed by a personal computer (PC), and the analyzed results are confirmed on a PC display screen and in an output format.
The second problem is addressed to the handling of accelerations applied to the transportation container, its vibroisolating system, and the transported object, and the pulse durations (frequencies) of the accelerations.
An example of the second problem will be described below with respect to the relationship between the soundness of a nuclear fuel assembly and an acceleration applied thereto while the nuclear fuel assembly is being transported and handled.
Usually, an acceleration (G value) is applied at all times to a nuclear fuel assembly being transported from the transporting means such as a truck and the transportation container. The acceleration (G value) is roughly classified into two types. One type of acceleration is a temporary, i.e., unsteady, large impact acceleration intermittently applied from the truck or the transportation container to the fuel assembly.
The other type of acceleration is a steady relatively small sustained acceleration continuously applied from the truck or the transportation container to the fuel assembly.
These two types of acceleration affect the soundness of nuclear fuel assemblies being transported as follows: The temporary, i.e., unsteady, large impact acceleration intermittently applied to the fuel assembly has large adverse effects on the soundness of nuclear fuel assemblies being transported with regard to changes in the gap between fuel rods, axial motions of fuel rods, and damages such as bending of fuel rods in the fuel assembly and cracking and breaking of pellets in the fuel rods, which cannot be recognized from the appearance of the fuel assembly.
The steady relatively small sustained acceleration has large effects on damages such as fretting on the surfaces of fuel rods within the spacers.
“Allowable thresholds” or “allowable limit values” for accelerations (both steady and unsteady) which cause damage to the soundness of nuclear fuel assemblies have been evaluated and calculated for the respective nuclear fuel assemblies. With respect to the transportation of general cargoes other than nuclear fuels and precision apparatus, it is the current practice to uniquely evaluate that the transported product has no quality or performance problem if the acceleration (G value) applied to the transportation container or product has not exceeded the allowable limit value even once.
If, however, an acceleration in excess of the allowable limit value has been applied to the transported product even once due to the dropping of the product, for example, while the product is being transported, then the product is apparently damaged or plastically deformed in some way. Therefore, it is necessary to take some precautions not to allow an acceleration in excess of the allowable limit value to be applied to the product being transported or handled. This concept has heretofore been relied upon, and has been realized by a process of storing accelerations in excess of a predetermined allowable limit value and a process of selecting one of two alternatives YES, NO using a mechanical sensor such as an ON/OFF accelerometer. According to these processes, one of the two states, i.e., whether the applied acceleration has exceeded the allowable limit value or not, is detected.
However, the soundness of a nuclear fuel assembly or a precision apparatus while it is being handled or transported cannot simply be determined as being free of any problems or as being adversely affected when the applied acceleration has not exceeded the allowable limit value.
In particular, fretting on the surface of fuel rods of a nuclear fuel assembly is caused when the fuel rods and the spacer rings rub against each other due to vibrations while the nuclear fuel assembly is being transported.
More fretting tends to occur when a steady continuous acceleration greater than a certain value is applied to the nuclear fuel assembly than when a temporary impact acceleration greater than a predetermined acceleration level is intermittently applied to the nuclear fuel assembly while the nuclear fuel assembly is being transported. The nuclear fuel assembly which suffers such fretting cannot have a guaranteed product quality.
A steady continuous acceleration greater than a certain value is different from a temporary impact acceleration in excess of an allowable threshold, i.e., an allowable limit value, and is not an acceleration which causes damage or plastic deformation to a product when it is applied in excess of an allowable limit value even once when the product is dropped while it is being handled or while the product is being transported.
Usually, a steady continuous acceleration has a smaller absolute value, but occurs frequently, whereas an intermittent temporary unsteady large impact acceleration has a large absolute value, but occurs less frequently.
Even if an applied acceleration does not exceed an allowable limit value even once, but occurs many times, i.e., the accumulated value of pulse durations of generated accelerations is large, in the vicinity of the allowable limit value, then since the accumulated value of vibration energy of the imposed acceleration is large, it apparently poses a serious problem on the soundness of the product. Consequently, even though the applied acceleration does not exceed the allowable limit value, if the accumulated value of vibration energy of the acceleration imposed on the fuel rods of a nuclear fuel assembly is large, then damage to the fuel components, particularly fretting, is increased to the extent that the soundness of the nuclear fuel assembly as the product cannot be guaranteed.
Therefore, the vibration energy that affects the soundness of a nuclear fuel assembly while it is being handled and transported should be considered in view of both the magnitude of the applied acceleration and the frequency thereof.
The conventional problems have been described above from the standpoints of the magnitude of the applied acceleration and the frequency thereof. Now, the correlation between a generated acceleration (G value) and a frequency (Hz) will be reviewed in connection with the soundness of a nuclear fuel assembly.
It is a well known fact that an acceleration is necessarily frequency-dependent. For example, an acceleration which is applied to a product when the product drops is a temporary impact acceleration, and has its frequency in a high frequency range.
On the other hand, an acceleration applied to a transportation container or a product stored therein while it is being transported on land or sea is dominantly a steady acceleration in a low frequency range. However, an acceleration transmitted from a vehicle engine to a transportation container or a product stored therein has its frequency range often depending on the rotational speed of the engine, mostly less than 100 Hz. Therefore, a review of the pulse duration of an acceleration applied to a nuclear fuel assembly indicates what kind of acceleration is applied to the nuclear fuel assembly.
An object has an inherent natural frequency. A product (object) which is transported has its natural frequency governed by a state in which it is fastened to a container.
It has been confirmed by transportation tests and vibration tests that a nuclear fuel assembly as fastened to its transportation container has its natural frequency ranging from 20 Hz to 70 Hz.
An acceleration applied to a nuclear fuel assembly while it is being transported and handled is transmitted through the transporting means (a truck or the like) and the transportation container to the nuclear fuel assembly. If the acceleration applied to the nuclear fuel assembly is in a frequency range from 20 Hz to 70 Hz, then since the frequency is the same as the natural frequency of the nuclear fuel assembly, the nuclear fuel assembly resonates within the transportation container.
When the acceleration applied from the transportation container to the nuclear fuel assembly is in a frequency range from 20 Hz to 70 Hz and has its G value smaller than the allowable limit value, the fuel rods of the nuclear fuel assembly are subjected to amplified vibrations at an acceleration several times greater than the applied acceleration because of the resonance of the fuel rods. The acceleration (G value) which is caused by the amplified vibrations of the fuel rods is often much greater than the allowable threshold or the allowable limit value.
As a consequence, simply because an acceleration (G value) measured on the truck floor or the transportation container is lower than the allowable threshold or the allowable limit value does not necessarily mean that the acceleration (G value) of the fuel rods is lower than the allowable threshold when the measured acceleration is applied to the nuclear fuel assembly.
If the frequency range of the acceleration applied to the truck floor or the transportation container is confirmed to be out of the range from 20 Hz to 70 Hz, i.e., to be not the same as the natural frequency range of the nuclear fuel assembly, then since the acceleration applied to the fuel rods of the nuclear fuel assembly is not amplified, it can be confirmed that the acceleration applied to the fuel rods is lower than the allowable threshold, i.e., the allowable limit value. In this case, the nuclear fuel assembly, i.e., the fuel rods and the fuel components, is normal, and the fuel rods are not bent or abnormally deformed within the spacers.
Though the frequency range of the acceleration applied to the truck floor or the transportation container is in the range from 20 Hz to 70 Hz and the acceleration (G value) produced by the amplified vibrations of the fuel rods is not in excess of the allowable threshold, i.e., the allowable limit value, because the applied acceleration itself is small, if the fuel rods has resonated for a certain period of time, then the vibration energy applied to the fuel rods is increased as described above, causing the spacer rings and the fuel rods to rub against each other. As a result, the fretting on the fuel rods is increased to the extent that the soundness of the nuclear fuel assembly as the product cannot be guaranteed.
For judging the soundness of the nuclear fuel assembly while it is being transported and handled, it is necessary to confirm the magnitude and frequency of the acceleration applied to the nuclear fuel assembly, whether the applied acceleration is a steady acceleration or a temporary unsteady acceleration, and whether the frequency range of the applied acceleration is in agreement with the natural frequency range of the nuclear fuel assembly or not.
The third problem of the conventional process is that a measuring system and method for confirming the transportation status of a transported object and the quality of the transported object is put into operation after the completion of the transportation of the object, and only two types of data, i.e., temperature, humidity, gas concentration, acceleration G value, and pulse duration data which have exceeded predetermined values (trigger levels) for quality guarantee and time data of those data, i.e., values in excess of trigger levels and times when such values have occurred are employed to determine results.
When radioactive objects such as nuclear fuel substances or dangerous objects are transported, it is the present practice for the driver of the transporting vehicle or an occupant of a security vehicle for guarding the transporting vehicle to confirm the safety of the object in transportation indirectly with a detected quantity indicative of a level of danger.
According to the above present safety confirming process, since the measured data cannot be confirmed in real-time while the object is being transported, the safety of the transportation is confirmed by the detected quantity of the confirming and inspecting data after the transportation. If the soundness of the transporting means, the fastened state, and the transportation container is impaired due to some trouble during the transportation of the object, then an event impairing the quality of the object during the transportation occurs, and the quality degradation of the object changes from a low level to a high level as time goes by during the transportation.
Immediately before the transported object arrives at the destination, the quality of the object is seriously degraded, possibly resulting in a serious accident or a situation where the object can no longer be used.
If the transported object and its status during the transportation can be monitored in real-time by the transporter and the remote object monitoring office based on bidirectional communications, and measured data representing an event which causes a light level of damage impairing the quality of the object being transported can be confirmed during the transportation and exchanged in real-time by the driver, the security personnel, and the remote object monitoring office, then certain countermeasures can be taken when the transported object, the transporting means, the transportation container, and the transporting and handling status are damaged at a low level, thus preventing a serious accident from happening and also preventing the object from being degraded in quality during the transportation.
It is preferable to transmit measured waveform data for confirming the quality of an object being transported, i.e., temperature, humidity, gas concentration, acceleration/pulse duration (frequency) data in excess of trigger levels, and time and location data representing the times when and locations where those data are produced, to a server via a dedicated or general wired or wireless communication network, and to confirm those measured data supplied from the server through the Internet Web bidirectionally in real-time at a control center in the object monitoring office or on a PC of inspecting personnel.
The fourth problem of the conventional process is that even though the measured data can be confirmed via the Internet Web on a PC screen or in an output format, the data obtained from the measurement system are expected to be primarily two types of data, i.e., measured data such as temperature, humidity, acceleration, and gas concentration data in excess of trigger levels, which tend to impair the quality of the object being transported, or measured data capable of judging a level of damage, and time data indicative of times when those measured data are produced. With such a system, the above procedure for confirming measured data at the control center in the object monitoring office or on the PC of inspecting personnel is not as effective as intended.
Even if temperature, humidity, acceleration, and gas concentration data tending to impair or damage the soundness of the object being transported and their time data can be confirmed in real-time via the Internet Web on a PC screen or in an output format, only the measured data for confirming the quality of the transported object or indicating a level of damage thereto and their time data are not enough to accurately determine the status and level of damage to the transported object and possible countermeasures in the absence of specific video images or camera-captured images capable of confirming the fastened state of the container and the soundness of the container itself in positions and states where the transporting means has traveled. When an accident occurs, it is effective to send data for determining the soundness of the container in real-time from a CCD camera which captures images at the time of the accident.
Specifically, it is necessary to display measured data relative to the object being transported, i.e., measured data such as temperature, humidity, acceleration, and gas concentration data in excess of trigger levels tending to impair the quality of or damage the object being transported and their time data, supplied in real-time via the Internet Web, together with positional information of traveling vehicles obtained from a GPS, over a map on a PC screen or in a monitor output format.
It is also necessary that if data in excess of a trigger level is measured, a CCD camera on the transporting vehicle be automatically turned on to capture images of a transportation status, a container fastening status, a container soundness status, an accident status, which provide a basis for determining the soundness of the object, and data of the captured images, and the measured and time data supplied in real-time via the Internet Web, together with positional information of traveling vehicles obtained from a GPS, and traveled position data, be displayed over a map on a PC screen or in a printed output format.
The fifth problem of the conventional process is that, as partly described above with respect to the fourth problem, accurate positional information while the transporting vehicle is travelling cannot be obtained because the locations where the data indicative of the soundness of the transported object and the transportation container can be judged only at times when those data are produced.
If measured data in excess of a trigger level can be displayed over a map and the distance traveled from the start of the transportation can also be displayed, then the location of the transported object can be identified over the map on the PC screen together with the measured waveform data tending to affect the object being transported. The positional information thus displayed makes it possible to avoid any problematic routes in a future transportation plan, and also to indicate the identified position to a following transporting vehicle which is actually traveling. The following transporting vehicle can then limits its speed to lower any accelerations applied to the transported object, thus keeping the soundness of the object in a desired level.
Conventional problems which occur in actual transporting sessions will be described below.
The first problem of the conventional system is that since bidirectional communications between a transporting car which transports nuclear fuel assemblies and substances or an accompanying security vehicle and a nuclear fuel control center are performed entirely by telephonic conversations, the transmission of traveling positions of the transporting car, times when the transporting car passes through those traveling positions, and transportation statuses suffers the following drawbacks:
1) Since the information is transmitted via telephone, the bidirectional communications are made between a few people, and it takes a certain time for the information to reach every relevant staff member in the competent organization.
2) The information suffers a lack of accuracy and confidentiality because the information is transmitted from person to person via telephonic bidirectional communications. Specifically, inasmuch as information about a passing point applied for and an expected time at which a transporting vehicle will pass through the passing point, together with information as to how many minutes the transporting vehicle leads or lags behind the expected time, are transmitted via telephone to many persons involved, from time to time before several minutes prior to the arrival at the passing point, accurate information is often not transmitted to every relevant person.
3) Since it takes a time to transmit information, new corrected latest information is transmitted before the information reaches every relevant staff member in the competent organization. Therefore, the transmitted information suppers a reliability problem.
4) Telephonic information transmission may not be performed continuously in real-time at all times for 24 hours, but may be carried out intermittently at intervals of 30 minutes to 1 hour. Between such intermittent communication events, the control center is unable to recognize any transportation status of the transporting vehicle and hence has no information at all about the transporting vehicle. If any accident arises between the intermittent communication events, then the control center may not be accurately aware of the location and time of the accident. Since there are some time zones in which telephonic communications are unidirectional from the transporting vehicle, but not bidirectional between the transporting vehicle and the control center, the control center may fail to recognize the accurate present position of the transporting vehicle occasionally.
The first problem of the conventional system is that if the transporting vehicle carrying nuclear fuel assemblies or substances and accompanying security vehicles travel along a wrong route different from the traveling route which has been applied for with a relevant organization, then the control center cannot confirm the travel along the wrong route, and the driver of the transporting vehicle cannot confirm the travel along the wrong route, but keeps on traveling along the wrong route. Sometimes, the driver of the transporting vehicle may recognize the travel along the wrong route when the driver informs the control center of a time at which the transporting vehicle is expected to pass through a passing point which has been applied for.
The third problem of the conventional system is that bidirectional communications between the transporting vehicle and the control center are continuous and may be interrupted for a period ranging from 30 minutes to 1 hour. If the transporting vehicle suffers a serious impact accident within the interrupted period, then the following disadvantages occur:
1) If an accident takes place in an interrupted period from 30 minutes to 1 hour during telephonic bidirectional communications, then the control center is unable to accurately confirm the position of the accident. The control center cannot even confirm accurately the exact location of the accident based on telephonic communications from the transporting vehicle that has suffered from the accident, and hence cannot accurately confirm details of the accident.
2) In view of special circumstances of an emission of nuclear fuel substances upon an accident, it is necessary to confirm in real-time the locations of police departments, schools, hospitals, city, town, and village offices within a circle of several km around the spot of the accident. Those locations are indicated via telephonic communications from accompanying security vehicles or other cars near the spot of the accident. From that time on, the competent organization starts checking information on major facilities within the circle of several km on a map covering the spot where the accident is expected to have occurred. Therefore, it takes a considerable time to obtain the desired information, and the transmission of accurate real-time information is delayed.
The fourth problem of the conventional system is that the competent authority requires that a container storing nuclear fuel assemblies or substances be sealed when they are transported or stored. If the sealing of the container is broken for some reason, then detailed information about the unsealing of the container, i.e., the time zone and the environment in which the container is unsealed, is required by the competent authority.
At present, the sealing of a container is periodically checked by the worker while the container is being stored. When the sealing of the container is broken for some reason, no detailed information about the unsealing of the container, i.e., the time zone and the environment in which the container is unsealed, is known, and the fact that the container has been unsealed remains.